Node_exporter: on Raspberry Pi: err="error parsing mdstatus: error parsing mdstat /proc/mdstat: open /proc/mdstat: no such file or directory"

[vielmetti]

Host operating system: output of uname -a

Linux piaware 4.19.97-v7+ #1294 SMP Thu Jan 30 13:15:58 GMT 2020 armv7l GNU/Linux

node_exporter version: output of node_exporter --version

node_exporter, version 1.0.0 (branch: HEAD, revision: b9c96706a7425383902b6143d097cf6d7cfd1960)
  build user:       root@3e55cc20ccc0
  build date:       20200526-06:03:58
  go version:       go1.14.3

node_exporter command line flags

./node_exporter --web.listen-address="100.xx.xx.xx:9100" &

Are you running node_exporter in Docker?

What did you do that produced an error?

System is producing statistics, but I'm getting an error ever poll from mdstat

level=error ts=2020-05-26T20:15:43.377Z caller=collector.go:161 msg="collector failed" name=mdadm duration_seconds=0.000192865 err="error parsing mdstatus: error parsing mdstat /proc/mdstat: open /proc/mdstat: no such file or directory"

What did you expect to see?

No errors in logfile for default distribution

What did you see instead?

complaints about mdstat

[vielmetti]

The documentation states

Exposes statistics about devices in /proc/mdstat (does nothing if no /proc/mdstat present).

so I think this is genuinely a bug, either in the docs (to warn you to disable it), or in the code (to skip the metric if the file is not found).

[SuperQ]

Yes, this looks like a bug in the upstream procfs library that parses the mstat file. Should be easy to fix. For now, you can manually disable the collector with --no-collector.mdadm to avoid the log noise.

[discordianfish]

Meh.. that's unfortunate right after 1.0..
@SuperQ Should we have tests to catch these kind of issues?